Suture anchor system with compressible distal tip

ABSTRACT

Methods and devices for fixation of soft tissue to bone are provided. In one embodiment, a suture anchor is provided having an elongate cylindrical body with proximal and distal ends and an inner lumen extending therethrough. The elongate body can be configured so that upon partial insertion into a bone hole, it is securely anchored within the bone hole and a suture extending through the inner lumen is freely slidable. It can also configured so that, upon further insertion into the bone hole, at least a portion of the elongate body compresses to lock the suture within the inner lumen such that the suture is prevented from sliding. In another embodiment, a suture anchor is provided having arms that have an open position for receiving a suture therebetween, and a closed position in which the suture is retained but allowed to slide freely.

FIELD OF THE INVENTION

The present invention relates generally to medical devices andprocedures, and more particularly to systems and methods for attachingsoft tissue to bone.

BACKGROUND OF THE INVENTION

The complete or partial detachment of ligaments, tendons and/or othersoft tissues from their associated bones within the body are relativelycommonplace injuries, particularly among athletes. Such injuries aregenerally the result of excessive stresses being placed on thesetissues. By way of example, tissue detachment may occur as the result ofan accident such as a fall, over-exertion during a work-relatedactivity, during the course of an athletic event, or in any one of manyother situations and/or activities.

In the case of a partial detachment, the injury will frequently healitself, if given sufficient time and if care is taken not to expose theinjury to further undue stress. In the case of complete detachment,however, surgery may be needed to re-attach the soft tissue to itsassociated bone or bones. Numerous devices are currently available tore-attach soft tissue to bone. Examples of such currently availabledevices include screws, staples, suture anchors, and tacks. In softtissue re-attachment procedures utilizing screws, the detached softtissue is typically moved back into its original position over the bone.Then the screw is screwed through the soft tissue and into the bone,with the shank and head of the screw holding the soft tissue to thebone. Similarly, in soft tissue re-attachment procedures utilizingstaples, the detached soft tissue is typically moved back into itsoriginal position over the bone. Then the staple is driven through thesoft tissue and into the bone, with the legs and bridge of the stapleholding the soft tissue to the bone.

In soft tissue re-attachment procedures utilizing suture anchors, ananchor-receiving hole is generally first drilled in the bone at thedesired point of tissue re-attachment and a suture anchor is deployed inthe hole using an appropriate installation tool. This effectively locksthe suture to the bone, with the free end(s) of the suture extending outof the bone. The free ends of the suture are passed through or aroundthe soft tissue and are used to tie the soft tissue securely to thebone.

There remains a need for improved methods and devices for attaching softtissue to bone.

SUMMARY OF THE INVENTION

The present invention generally provides methods and devices foranchoring soft tissue to bone. In one embodiment, methods and devicesare providing having independent mechanisms for fixation of a sutureanchor in bone and for fixation of a tension applied to a sutureextending between the suture anchor and the tissue being secured. Byseparating these mechanisms, the present invention allows for lessdependence on the interface between the anchor and the bone and greatercontrol over suture tensioning. In an exemplary embodiment, the sutureanchor is partially inserted and fixed in the bone prior to tensioningthe suture. This can provide a better perspective of the finished stateof the repair tension and provide the ability to add or release tensioneven after fixation of the suture anchor.

In one embodiment, a suture anchor is provided having an elongatesubstantially cylindrical body having a proximal portion with at leastone bone-engaging surface feature formed on an external surface thereof,a flexible distal portion, and an inner lumen extending through theproximal and distal portions. The elongate body can be configured suchthat, upon insertion of the distal portion into a bone hole andengagement of at least one of the at least one bone-engaging surfacefeatures with the bone hole, a suture extending through the inner lumenand coupled to the distal portion is freely slidable. The elongate bodycan further be configured such that, upon further insertion into thebone hole, the distal portion of the elongate body compresses radiallyinward to lock the suture within the inner lumen such that the suture isprevented from sliding.

In one embodiment, when the distal portion of the elongate bodycompresses radially inward, an inner diameter of the proximal portion ofthe elongate body remains constant and an inner diameter of the distalportion of the elongate body decreases to lock the suture within theinner lumen. An outer diameter of the distal portion of the elongatebody can decrease in a distal direction. The distal portion of theelongate body can include, for example, first and second opposed armshaving planar inner surfaces that move toward one another when the firstand second opposed arms are compressed radially inward.

The elongate body can have a variety of configurations. For example, theat least one bone-engaging surface feature comprises a plurality ofcircumferential ribs formed on the proximal portion of the elongatebody. The elongate body can also have a bore extending through asidewall thereof and in communication with the inner lumen. In otheraspects, the inner lumen can include a suture-engaging member having atleast a portion that extends substantially transverse to an axis of theinner lumen, the suture-engaging member being configured to receive asuture there around. The suture-engaging member can have a bore formedtherethrough such that a suture can pass through the suture-engagingmember. In an exemplary embodiment, the suture-engaging member isU-shaped, and the suture-engaging member extends substantially parallelto opposed planar inner surfaces of the distal portion of the elongatebody.

In another embodiment, a suture anchor is provided having an elongatebody having proximal and distal ends and an inner lumen extendingtherethrough. The elongate body can have a drive feature on the proximalend thereof for mating with a driver, at least one bone-engaging surfacefeature formed on an external surface thereof and configured to engagebone, and a flexible distal tip portion configured to be compressed whenadvanced into a bone hole to engage a suture extending therethrough. Theflexible distal tip portion can have various configurations, and in oneaspect the tip has opposed planar inner surfaces configured to engage asuture therebetween when the flexible distal tip portion is compressed.The tip portion can taper radially inward such that an outer diameterdecreases in a distal direction. In other aspects, the inner lumen caninclude a suture-engaging member extending substantially transverse toan axis of the inner lumen. The suture-engaging member can optionallyhave a lumen extending therethrough such that the suture can passthrough the suture-engaging member.

In other aspects, a method for anchoring tissue to bone is provided andincludes advancing a bone anchor partially into a bone hole such thatthe anchor engages the bone and is secured within the bone hole. Thebone anchor can have a suture extending through an inner lumen of thebone anchor and coupled to a distal portion of the bone anchor. With thebone anchor partially advanced into the bone hole, the suture can betensioned to tension tissue coupled to the suture. After tensioning, thebone anchor can be further advanced into the bone hole to cause thedistal portion of the bone anchor to compress radially inward and lockthe suture therein. In one embodiment, at least one bone engagingsurface feature on a proximal portion of the bone anchor engages bonewhen the bone anchor is partially advanced into the bone hole. Inanother embodiment, the suture can be threaded through the inner lumenof the bone anchor and through a bore in a sidewall of the bone anchor,or the suture can be threaded around a suture-engaging member extendingacross the inner lumen of the bone anchor.

In another embodiment, a suture anchor is provided having an elongatebody with proximal and distal ends and an inner lumen extendingtherethrough. The elongate body can have a drive feature on the proximalend thereof for mating with a driver. The elongate body can also have aslot in the distal end defining first and second offset tips that arespaced a distance apart from one another to allow a suture to bereceived therebetween. The first offset tip can have a first planarsurface that is configured to be in sliding contact with a first planarsurface of the second offset tip upon compression of the distal end.When the distal tip is compressed and the planar surfaces of the firstand second offset tips are in contact with one another, the offset tipscan define an eyelet that is configured to retain a suture therein whileallowing free sliding movement of the suture relative to the eyelet.

The elongate body can have a number of configurations. For example, inone embodiment, the elongate body can have at least bone-engagingsurface feature formed on at least a proximal portion thereof. Inanother embodiment, an external surface of each of the first and secondoffset tips can be free of surface features. In one embodiment, theelongate body can include opposed substantially planar outer surfacesformed along a proximal portion thereof.

In another embodiment, the first offset tip can have a second planarsurface that extends transverse to the first planar surface of the firstoffset tip, and the second offset tip can have a second planar surfacethat extends transverse to the first planar surface of the second offsettip. The first and second planar surfaces of each of the first andsecond offset tips can be connected by a third substantially cylindricalsurface. In other aspects, the first and second offset tips each canhave a distal portion with a substantially triangular cross-sectionalshape. The first and second offset tips can be positioned on opposedsides of a longitudinal axis of the inner lumen when the elongate bodyis not compressed. The first and second offset tips can each have adistal portion with a width that is greater than a width of a proximalportion of the offset tip.

In another embodiment, a suture anchor is provided having an elongatebody with first and second substantially cylindrical outer surfaces onopposed sides thereof, and first and second substantially planarsurfaces on opposed sides thereof and extending between the first andsecond substantially cylindrical outer surfaces. The anchor can alsohave first and second arms extending distally from a distal end of theelongate body, the first and second arms being movable between a firstposition in which the first and second arms are spaced a distance apartfrom one another to define a slot therebetween for receiving a suture,and a second position in which a planar surface on each of the first andsecond arms are in sliding contact with one another to form an enclosedeyelet between the first and second arms for capturing a suturetherebetween.

The first and second arms can have a number of configurations. In oneembodiment, the first and second arms can each have a substantiallytriangular cross-sectional shape. The first and second arms can bepositioned on opposed sides of a longitudinal axis of the elongate bodywhen they are in the first position, and they can intersect thelongitudinal axis of the elongate body when they are in the secondposition. In other aspects, the first and second arms can each have aproximal portion with a maximum width that is less than a maximum widthof a distal portion of the first and second arms. The first and secondarms can each include a protrusion formed on a distal end thereof, eachprotrusion having the planar surfaced formed thereon.

In one embodiment, the planar surface on each arm can comprise a firstplanar surface, and each arm can include a second planar surface thatextends in a plane that is transverse to a plane containing the firstplanar surface. The first and second planar surfaces on each of thefirst and second arms can be connected by a third substantiallycylindrical surface. The planes containing the first and second planarsurfaces can extend in a direction substantially parallel to alongitudinal axis of an inner lumen extending through the elongate body.In other aspects, the substantially cylindrical outer surfaces of theelongate body can have threads formed thereon for engaging bone. Inother aspects, the substantially cylindrical outer surfaces of theelongate body can have a plurality of ridges formed thereon for engagingbone.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more fully understood from the following detaileddescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1A is a perspective view of one embodiment of a suture anchor;

FIG. 1B is a cross-sectional view of the suture anchor of FIG. 1A;

FIG. 1C is a partially transparent view of the suture anchor of FIG. 1Ahaving a suture extending therethrough;

FIG. 2A is a perspective view of another embodiment of a suture anchorsimilar to the suture anchor of FIG. 1A, but having a suture-engagingmember positioned more proximal;

FIG. 2B is a is a cross-sectional view of the suture anchor of FIG. 2A;

FIG. 3 is a cross-sectional view of another embodiment of a sutureanchor similar to FIG. 1A, but having a bore formed through thesuture-engaging member;

FIG. 4 is a perspective view of yet another embodiment of a sutureanchor having a suture-engaging member formed on an arm of a flexibledistal tip

FIG. 5 is a side view of another embodiment suture anchor similar toFIG. 1A, but having surface features for facilitating engagement of asuture;

FIG. 6A is a side view of a suture anchor according to anotherembodiment, having a bore formed through an arm of a flexible distaltip;

FIG. 6B is a cross-sectional view of the suture anchor of FIG. 6A;

FIG. 7 is a cross-sectional view of another embodiment of a sutureanchor having a bore extending through a sidewall of a proximal portionof the suture anchor;

FIG. 8 is a cross-sectional view of another embodiment of a sutureanchor having an elongate lumen extending through a sidewall of thesuture anchor;

FIG. 9A is a partially transparent side view of the suture anchor ofFIG. 1C shown partially inserted into a bone hole;

FIG. 9B is a side view of the suture anchor of FIG. 9A shown fullyinserted into the bone hole;

FIG. 10A is a cross-sectional view of another embodiment of a sutureanchor;

FIG. 10B is a side view of the suture anchor of FIG. 9A;

FIG. 10C is a top view of the suture anchor of FIG. 9A inserted in abone hole;

FIG. 10D is a bottom view of offset tips of the suture anchor of FIG.9A; and

FIG. 10E is an enlarged view of the distal portion of the suture anchorof FIG. 10A shown inserted into a bone hole.

DETAILED DESCRIPTION OF THE INVENTION

Certain exemplary embodiments will now be described to provide anoverall understanding of the principles of the structure, function,manufacture, and use of the devices and methods disclosed herein. One ormore examples of these embodiments are illustrated in the accompanyingdrawings. Those of ordinary skill in the art will understand that thedevices and methods specifically described herein and illustrated in theaccompanying drawings are non-limiting exemplary embodiments and thatthe scope of the present invention is defined solely by the claims. Thefeatures illustrated or described in connection with one exemplaryembodiment may be combined with the features of other embodiments. Suchmodifications and variations are intended to be included within thescope of the present invention.

The present invention generally provides methods and devices foranchoring suture to bone. In one embodiment, a suture anchor is providedand it includes an elongate substantially cylindrical body havingproximal and distal ends and an inner lumen extending therethrough. Theelongate body has a proximal portion that is configured to engage bone,and a distal portion that is configured to receive a suture therein, andto flex and engage the suture. In use, upon partial insertion into abone hole, the proximal portion can engage bone to securely anchor thesuture anchor within the bone hole, and the distal portion allows asuture extending through the inner lumen to be freely slidable. Uponfurther insertion of the elongate body into the bone hole, the distaltip portion can compress radially inward to lock the suture within theinner lumen such that the suture is prevented from sliding. Such aconfiguration is particularly advantageous as it allows a tension of thesuture to be adjusted after the bone anchor is engaged in the bone hole.Once the tension is properly adjusted, the tension can be locked bysimply further driving the anchor into the bone hole.

FIGS. 1A-1B illustrate one embodiment of a suture anchor 10 having anelongate body that is configured to be partially inserted into a bonehole and to allow free slidable movement of a suture extendingtherethrough, and to be fully inserted into a bone hole to engage andlock the suture therein. In general, the suture anchor 10 has anelongate body with proximal and distal ends 10 p, 10 d and an innerlumen 20 extending therethrough. A proximal portion 12 of the elongatebody can have a generally cylindrical shape and can be configured toengage bone to anchor the suture anchor 10 within a bone hole. A distalportion 14 of the elongate body can be flexible or compressible to allowa suture extending therethrough to slide freely when the distal portion14 is resting and not compressed, and to be secured or locked in a fixedposition when the distal portion 14 is compressed.

The proximal portion 12 of the elongate body can have a variety ofconfigurations. In an exemplary embodiment, as indicated above, theproximal portion 12 is configured to engage bone. As such, the proximalportion 12 is preferably substantially rigid, and can have a generallycylindrical shape to allow the proximal portion 12 to fit securelywithin a cylindrical bone hole. While not shown, the proximal portion 12can, however have one or more planar sidewalls, grooves, or othersurface variations.

In order to facilitate engagement of bone, the proximal portion 12 caninclude one or more bone-engaging surface features formed on an externalsurface thereof for securely anchoring the suture anchor 10 within abone hole, even when the suture anchor is only partially inserted. Asshown in FIGS. 1A-1B, the proximal portion 12 includes a plurality offlanges 32 circumferentially formed around the external surface of theanchor, and spaced axially along the anchor. While the bone-engagingsurface features in the illustrated embodiment are in the form of aplurality of circumferential axially-spaced flanges, a person skilled inthe art will understand that one or more of various surface-engagingfeatures can be used, such as teeth, ridges, threads, barbs,protrusions, etc. The surface-engaging features 32 can be located on theentire external surface of the suture anchor 10, or on any portionthereof. In an exemplary embodiment, as shown, the flanges 32 or othersurface-engaging features are formed around only the proximal portion 12and extend from the proximal end 10 p and terminate just proximal to thedistal tip portion 14, which is free from surface-engaging features.Such a configuration allows the distally-positioned flanges 32 to engagebone when the suture anchor 10 is only partially inserted into a bonehole, while the distal tip portion 14 remains free to flex. Theparticular location along the elongate body at which thesurface-engaging features 32 terminate can vary depending on theparticular configuration of the suture anchor 10.

The inner lumen 20 that extends through the elongate body can also havea variety of configurations, but the inner lumen 20 is preferablyconfigured to receive one or more sutures therein. The inner lumen canalso be configured to receive a driver for driving the suture anchor 10into the bone. As shown in FIG. 1B, the inner lumen 20 has a firstdiameter d_(i) at a proximal portion thereof that is greater than adiameter d_(j) at a distal portion thereof, such that the proximalportion of the inner lumen 20 can receive a driver. Various techniquescan be used to facilitate engagement between the inner lumen and adriver mechanism. For example, the inner lumen, or at least the proximalportion thereof, can have an asymmetrical shape that complements acorresponding asymmetrical shape of a driver. The asymmetrical portionpreferably extends along a substantial length of the inner lumen so asto maximize surface contact between a driver and the suture anchor.While not shown, the proximal portion of the inner lumen 20 can havevarious shapes and sizes, such as hexagonal, to allow it to be keyed toa driver. A person skilled in the art will appreciate that, while aheadless suture anchor is shown, the proximal end 10 p of the sutureanchor 10 can alternatively have a head formed thereon and configured tomate with a driver.

As indicated above, the suture anchor 10 has a flexible distal tipportion 14 that is configured to compress upon insertion into a bonehole and to engage a suture extending therethrough. While the tip 14 canhave a variety of configurations, in an exemplary embodiment the tipportion 14 has a generally cylindrical outer surface. The outer diameterd_(t) of the tip portion 14 can remain substantially constant along theentire length thereof, and the diameter d_(t) can be greater than, lessthan, or equal to a minor diameter d_(o) of the proximal portion 12 ofthe suture anchor 10. Alternatively, FIG. 1C illustrates an embodimentof a suture anchor 10′ having a similar configuration to suture anchor10 (like reference numerals are used to refer to like parts), howeverthe tip portion 14′ is tapered distally such that an outer diameterd_(t)′ of the tip portion 14′ at the proximal end is greater than anouter diameter of the tip portion 14 at the distal end. In an exemplaryembodiment, the diameter of the distal tip portion is configured to aidin compression of the distal tip portion upon insertion into a bonehole, and more particularly into a bone hole having a tapered terminalend or a bone hole having a reduced-diameter region, as will bediscussed in more detail below.

To allow compression of the distal tip portion 14, the tip portion 14can include one or more longitudinally-oriented slots formed therein.The flexibility of the tip can vary depending on the number andconfiguration of the slots, and a person skilled in the art willappreciate that the tip can be configured to have a desired flexibility.While the size, quantity, position of slots can vary, in the illustratedembodiment the distal tip portion 14 has first and second axiallyopposed U-shaped slots 17 a, 17 b formed therein that define first andsecond opposed arms 16 a, 16 b. The length of the slots 17 a, 17 b canbe configured to provide a desired flexibility of the opposed arms 16 a,16 b. By way of non-limiting example, the slots 17 a, 17 b can extendalong about 20% to 50% of the entire length of the suture anchor 10. Forexample, the slots 17 a, 17 b can have a length in the range of about 3mm to 7 mm. The distal tip portion 14 can thus likewise have a lengththat is about 20% to 50% of the entire length of the suture anchor 10.In an exemplary embodiment, the distal tip portion 14 has a length inthe range of about 2 mm to 5 mm. Longer distal tips may provide betterfixation with a reduced risk of breakage.

The shape of each arm 16 a, 16 b can also vary. In an exemplaryembodiment, the outer surface of each arm 16 a, 16 b is generallycylindrical. The inner surface of the arms 16 a, 16 b, however, can varyto facilitate engagement of a suture extending therethrough. FIGS. 1A-1Cillustrates arms 16 a, 16 b having planar inner surfaces 18 a, 18 b,respectively. Such a configuration can allow the surfaces 18 a, 18 b toengage a suture therebetween when moved together during compression ofthe tip portion 14. As further shown in FIGS. 1A-1C, the distal-most endof the arms 16 a, 16 b, and thus of the tip portion 14, can be blunt orrounded to facilitate introduction into a bone hole.

The suture anchor 10 can also include one or more suture-engaging orreceiving members formed therein and configured to receive a suture. Thesuture-engaging member can have a variety of configurations, and it canbe integrally formed with the suture anchor, i.e., the suture anchor andsuture-engaging member can be molded as a single unit or formed from asingle piece of material, or the suture-engaging member can be fixedlyor removably mated to the suture anchor. The suture-engaging member canalso be rotatably disposed within the inner lumen.

In one embodiment, the suture-engaging member can be in the form of apost, pin, rod, or arm having at least a portion that extends across thelumen between opposed inner surfaces of the body. The particular shapeand location of the suture-engaging member can vary, but it ispreferably configured to receive a suture therearound to retain thesuture within the lumen 20, and more preferably within a distal portionof the lumen 20, e.g., between the opposed arms 16 a, 16 b. Asillustrated in FIGS. 1A-1C, the suture-engaging member 40 is in the formof a U-shaped member having opposed terminal ends (only one end 41 isshown in FIG. 1B) that are coupled to opposed inner surfaces of the bodyat a location just proximal to the slots 17 a, 17 b formed in the distaltip portion 14. The terminal ends of the suture-engaging member 40 arepreferably axially aligned with the slots 17 a, 17 b such that thesuture-engaging member 40 extends substantially parallel to the innerplanar surfaces 18 a, 18 b of each arm 16 a, 16 b. A mid-portion 42 ofthe U-shaped suture-engaging member 40 can extend transversely acrossthe inner lumen 20 in a direction substantially perpendicular to thelongitudinal axis of the inner lumen 20. It will be understood by aperson skilled in the art that the angular orientation of thesuture-engaging member can vary relative to a longitudinal axis of theinner lumen 20. In use, as shown in FIG. 1C, a suture 90′ can be wrappedaround the mid-portion 42′ of the suture-engaging member 40′, withterminal ends 90 a′, 90 b′ of the suture 90′ extending out of theproximal end 10 p′ of the suture anchor 10′.

The particular location of the suture-engaging member 40, and inparticular the mid-portion 42 of the suture-engaging member 40, withinthe inner lumen 20 can also vary. In the embodiment of FIGS. 1A-1C, themid-portion 42 of the suture-engaging member 40 is positioned distal ofthe terminal ends (only end 41 is shown) of the suture-engaging memberand distal to a proximal-most end of each slot 17 a, 17 b, such that themid-portion 42 is located between the flexible arms 16 a, 16 b of thedistal tip portion 14. Such a configuration will allow a suture 90extending around the mid-portion 42 to be engaged between the arms 16 a,16 b and the mid-portion 42 of the suture-engaging member 40.

FIGS. 2A-8 illustrate additional embodiments of suture anchors havingconfigurations similar to suture anchor 10, with various modifications.Like reference numerals are used to refer to like parts, with adifferent prefix used for each embodiment. The suture anchorsillustrated in FIGS. 2A-8 can thus have all of the features discussedabove with respect to FIGS. 1A-1C. Moreover, a person skilled in the artwill appreciate that a suture anchor according to the present inventioncan include any combination of features disclosed herein, including thefeatures discussed and illustrated with respect to FIGS. 2A-8.

FIGS. 2A-2B illustrates another embodiment of a suture anchor 200 inwhich the suture-engaging member 240 is located more proximal than theposition of the suture-engaging member 40 of FIGS. 1A-1B. In particular,in this embodiment the mid-portion 242 of the suture-engaging member 240is positioned closer to the proximal ends of the arms 216 a, 216 b, butyet still located distal of a proximal-most end of each slot 217 a, 217b extending between the arms 216 a, 216 b. The opposed terminal ends 241a, 241 b of the suture-engaging member 240 can be coupled to theproximal-most end of each slot 217 a, 217 b.

The suture-engaging member 240 can include various features formedthereon to facilitate positioning of a suture extending there around. Asshown in FIGS. 2A-2B, a distal-facing surface of the mid-portion 242(i.e., the portion extending generally transverse to the axis of thelumen) of the suture-engaging member 240 includes a groove or concavity243 formed therein and configured to seat a suture.

In another embodiment of a suture anchor 300, shown in FIG. 3, thesuture engaging member 340 can have a bore 343 formed therethrough suchthat one or more sutures can pass through the bore 343 and around oneside of the suture-engaging member 340. Such a configuration will allowa suture to be engaged between one arm 316 a and the suture-engagingmember 340.

In another embodiment of a suture anchor 400, as shown in FIG. 4, thesuture-engaging member 440 can be coupled to one arm, e.g., arm 416 b,of the distal tip portion 414. In this embodiment, the suture-engagingmember 440 is U-shaped with opposed terminal ends that are matedadjacent to opposed lateral sides of the arm 416 b. The suture-engagingmember 440 thus extends in a plane that is perpendicular to the innerplanar surface 418 b of the arm 416 b. Similar to anchor 300, the suture90 will be engaged between one arm, e.g., arm 416 a and thesuture-engaging member 440.

The arms of the flexible distal tip portion can also include otherfeatures to facilitate engagement of a suture. FIG. 5, for example,illustrates another embodiment of a suture anchor 500 that is similar toanchor 10, but that includes a surface protrusion 502 a, 502 b formed onthe inner planar surface 518 a, 518 b of each arm 516 a, 516 b of thedistal tip portion 514. The surface protrusions 502 a, 502 b can havevarious shapes and sizes and can be located anywhere along the arms 516a, 516 b. As shown in FIG. 5, the protrusions 502 a, 502 b are directlyopposite one another and are positioned just distal to the mid-portion542 (e.g., transversely extending portion) of the suture-engaging member540. Each protrusion 502 a, 502 b extends in a direction generallyparallel to a direction of the mid-portion 542 of the suture-engagingmember 540. The positioning of the protrusions 502 a, 502 b canfacilitate further engagement of a suture extending around thesuture-engaging member 540. For example, when the arms 516 a, 516 b arecompressed inward, the protrusions 502 a, 502 b can tilt proximally andengage a suture against the suture-engaging member 540. A person skilledin the art will appreciate that the inner planar surface 518 a, 518 bcan include other features, such as teeth, indentations, or a texturedsurface to facilitate engagement of a suture.

In other aspects, the suture anchor can include one or more bores,lumens, or pathways formed through a sidewall thereof for receiving thesuture. For example, FIGS. 6A-6B illustrate one embodiment of a sutureanchor 600 having a bore 608 extending through one of the arms 616 a ofthe flexible distal tip portion 614. The bore 608 is positioned adjacentto a distal-end of the arm 616 a to allow a suture 90 to extend throughthe lumen 620 of the suture anchor 600, pass through the bore 608, wraparound the distal-most end of the arm 616 a, and extend back through thelumen 620, as shown in FIG. 6B. In use, when the arms 616 a, 616 b arecompressed, the suture will be engaged directly between the arms 616 a,616 b. In another embodiment shown in FIG. 7, the proximal portion 712of the suture anchor 700 can have a bore 708 extending through thesidewall thereof to receive at least a portion of the suture 90therethrough. The bore 708 in this embodiment is located just distal ofthe proximal-most flange 732 a on the suture anchor 700. This will allowthe suture 90 to remain freely slidable when the suture anchor 700 ispartially inserted into bone, such that the bore 708 will not yet bedisposed within the bone hole. Once the anchor 700 is fully insertedinto a bone hole, the portion of the suture 90 extending out of the bore708 and along the outside of the suture anchor 700 will be engagedbetween the suture anchor 700 and the bone hole, thus providing anadditional means for fixation. A person skilled in the art willappreciate that the bore 708 can extend at any angle and can bepositioned at various locations. Moreover, rather than a bore 708, thesuture anchor can include a lumen. For example, in another embodiment ofa suture anchor 800 shown in FIG. 8, an elongate lumen 809 can extendthrough a sidewall of the suture anchor 800 and can communicate with theinner lumen 820. The lumen 809 can originate at a location within theflexible distal tip portion 814 adjacent to the suture-engaging member840, and the lumen 809 can exit in a sidewall of the anchor 800 at alocation just distal to the proximal end 810 p of the anchor 800. Such aconfiguration can function similar to suture anchor 700 described abovewith respect to FIG. 7. Alternatively, the lumen 809 can exit at theproximal-most surface of the suture anchor 800.

The suture anchors disclosed herein can be formed from variousbiocompatible materials including, by way of non-limiting example,metals, such as surgical grade titanium, and polymers, such aspoly-ether-ether-ketone (PEEK), polylactic acid, polyglycolic acid, andcombinations thereof. Exemplary materials include, by way ofnon-limiting example, a composite of tricalcium phosphate andpoly(lactic-co-glycolic acid), such as Biocryl Rapide™ available fromDePuy Mitek, Inc. The properties of the material can depend on theparticular configuration of the suture anchor. For example, the innerlumen of the suture anchor can have a length that maximizes the torquestrength of the suture anchor as well as the amount of surface contactbetween a driver and the suture anchor, thus allowing weaker materials,such as bioabsorbable and/or osteoconductive materials to be used. Acannulated suture anchor is also particularly advantageous as it allowsmaterials, such as bone-growth promoting materials, sealants, adhesives,etc., to be introduced therein to facilitate fixation. In oneembodiment, the material can have physical properties that aresufficient to allow a driver to be inserted into the inner lumen of thesuture anchor and to be used to drive the suture anchor into bonewithout damaging the suture anchor. The material can also have physicalproperties that are sufficient to allow compression of the elongate bodyof the suture anchor without damaging the suture anchor. In otheraspects, the material can allow directional compression, so thatalthough it is compressible in one plane, little to no compression canoccur in another plane. A person skilled in the art will appreciate thata variety of other materials, including plastics and metals, can be usedto form the suture anchor. Various portions of the suture anchor canalso be formed from different materials to provide distinct advantages.For example, the flexible distal tip portion can be formed from eitherthe same or different materials than the remainder of the suture anchor.In particular, the distal tip portion can be made of a material with agreater degree of flexibility or elasticity than the body, or portionsthereof, such as the bone-engaging surface members. In other aspects,portions of the suture anchor that engage with the bone hole, such asthe bone-engaging surface features formed on the external surface of theproximal portion of the suture anchor, can be made of a rigid,non-flexible material.

The present invention also provides exemplary methods for anchoringtissue to bone. While a method is described in connection with attachingsoft tissue to bone, the methods and devices disclosed herein can beused in a variety of medical procedures for anchoring one structure toanother. In general, a bone hole or tunnel is formed in bone of apatient. The diameter of the tunnel is preferably less than a majordiameter of the suture anchor, e.g., the thread or flange diameter, andsubstantially the same as the minor diameter of the suture anchor. Thelength of the tunnel can be the same as or slightly greater than alength of the suture anchor to allow the suture anchor to be fullydisposed thereon, however the length can vary depending on theconfiguration of the anchor. The hole can extend fully through thecortical bone to allow the suture anchor to be fully engaged through thethickness of the cortical bone. The bone hole can also extend into thecancellous bone depending on the length of the suture anchor. The bonehole can have various shapes depending on the configuration of thesuture anchor. In an exemplary embodiment, however, the bone hole istapered at its distal end to allow the tapered portion of the bone holeto compress the distal tip portion of the suture anchor as it is beingdriven into the bone hole.

One or more sutures can be coupled to the suture anchor using varioustechniques. As described above, the one or more sutures can have avariety of configurations, including being threaded through the innerlumen of the bone anchor, threaded through a bore or lumen in thesidewall of the bone anchor, threaded around a suture-engaging member,threaded through a suture-engaging member, threaded around a flexiblearm, or the suture(s) can enter and exit the same end of the anchor, orany combination of these. With reference to FIGS. 9A and 9B, whichillustrate suture anchor 10′ by way of non-limiting example, in oneembodiment the method can include coupling a suture 90 to a sutureanchor 10′ such that the suture 90 extends around a suture-engagingmember 40′ formed in the flexible distal tip portion 14′ of the sutureanchor 10 and trailing ends 90 a, 90 b of the suture 90 extend throughthe inner lumen 20′ and out the proximal end 10 p′ of the suture anchor10′.

Once the suture 90 is coupled to the anchor 10′, the distal tip of adriver (not shown) can be inserted into the lumen 20′ in the sutureanchor 10′. The trailing ends of the suture(s) can extend externallyalong the driver or they can extend through an inner lumen of thedriver. The driver can then be used to insert the suture anchor 10′ intothe bone hole BH. For example, where the suture anchor 10′ includesflanges 32′ formed thereon, the driver can be impacted to drive thesuture anchor 10′ into the bone hole. The flanges 32′ will engage thebone hole BH thereby preventing removal of the suture anchor 10′. Inother embodiments, the driver can be used to tap or rotate the boneanchor into the bone hole, and an interference fit, compression fit,and/or surface features, such as ribs, barbs, or protrusions, formed onthe suture anchor can be used to retain the suture anchor within thebone hole. In an exemplary embodiment, the suture anchor 10′ is insertedsuch that the entire distal tip portion 14′ is disposed within the bonehole BH and at least a portion of the bone-engaging surface features,e.g., one, two, or three flanges 32′, are disposed within the bone holeBH and in engagement with bone B, as shown in FIG. 9A. In an exemplaryembodiment, at least about 40% to 80% of the entire length of the sutureanchor 10′ is disposed within the bone hole during “partial” insertion.The anchor 10′ is preferably inserted only to a depth in which thesuture anchor 10′ is secured within the bone hole and will not pull out,and the distal tip portion 14′ is not compressed so that the sutureremains freely slidable to allow a tension on the suture to be adjusted.

Once the suture anchor 10′ is partially anchored within the bone hole,the suture 90 can be appropriately tensioned to apply the proper amountof tension to the attached tissue T. The trailing ends 90 a, 90 b of thesuture 90 can be used to anchor the soft tissue T to the bone B. Forexample, one or both trailing ends 90 a, 90 b of the suture 90 can beattached to a needle to allow the needle to be used to thread the suturethrough tissue to be anchor to the bone. The suture(s) can be threadedthrough tissue either prior to or after insertion of the suture anchorinto bone. Once the soft tissue is approximated toward the bone and thedesired tension is achieved, the driver can be used to further advancethe suture anchor 10′ into the bone hole BH. As shown in FIG. 9B, theshape of the bone hole BH will cause the flexible distal tip portion 14′to compress radially inward to lock the suture 90 within the inner lumen20′ such that the suture 90 is prevented from sliding. As shown, in thisembodiment the suture 90 is in direct engagement between the arms 16 a′,16 b′ and the suture-engaging member 40′.

FIGS. 10A-10D illustrate another embodiment of a suture anchor 100having a compressible distal tip portion that has an open configurationfor receiving a suture therein, and that upon insertion into a bonehole, closes to retain a freely slidable suture in an eyelet therein.The suture anchor 100 can have an elongate body with proximal and distalends 100 p, 100 d. A proximal portion 112 can be configured to engagebone, and a distal portion 114 can have opposed arms 116 a, 116 b can beconfigured to move together to form an eyelet 122 effective to retain asuture, such that the suture retained therein remains freely slidable.The suture anchor 100 can also have an inner lumen 120 extendingtherethrough, as shown in FIGS. 10A and 10C.

The proximal portion 112 of the suture anchor 110 can have a variety ofshapes and size, and in general can have the same configuration andfeatures as previously discussed above with respect to the sutureanchors of FIGS. 1A-8, including a drive feature 125 (FIG. 10A) formedin a proximal portion of the lumen 120 for mating with a driver, andbone-engaging surface features 132 located on an external surfacethereof. As further illustrated in FIG. 10C, the proximal portion 112 ofthe suture anchor 110 can also optionally include opposed planar outersurfaces 111 a, 111 b to create a gap when inserted in a bone hole BHfor receiving a suture 90, as shown. This can allow a suture positionedbetween the planar surface 111 a, 111 b and the bone hole BH to freelyslide to adjust tension.

The flexible distal arms 116 a, 116 b can also be similar to theprevious embodiment in that the arms 116 a, 116 b can extend distallyfrom the proximal portion 112 and are configured to move together uponcompression in a bone hole. In this embodiment, however, the distal arms116 a, 116 b can be configured to move between an open position shown inFIG. 10A, in which a suture can be passed through an opening 130 formedbetween the distal ends of the arms 116 a, 116 b, and a closed position,in which the arms 116 a, 116 b form an eyelet 123, shown in FIG. 10E, toprevent removal of the suture while still allowing free movement of thesuture.

While the arms 116 a, 116 b can have various shapes and sizes, as shownin FIG. 10D, the arms 116 a, 116 b can each be generally elongate withan enlarged distal tip 635 a, 635 b having a somewhat triangular shape,with one side being rounded. In particular, the outer surface 116 a_(o), 116 b _(o) of each tip 635 a, 635 b can be generally cylindrical,and each tip 635 a, 635 b can include first and second planar innersurfaces 116 a ₁, 116 a ₂, 116 b ₁, 116 b ₂. The first planar innersurface 116 a ₁, 116 b ₁ on each tip 635 a, 635 b can extend at an angleα relative to the second planar inner surface 116 a ₂, 116 b ₂ of eachtip 635 a, 635 b. The angle α can vary, but in an exemplary embodimentthe angle is in the range of about 45 degrees to 135 degrees, and morepreferably is about 90 degrees. The width of each planar surface canalso vary, but in an exemplary embodiment one of the first and secondplanar surfaces on each tip 635 a, 635 b has a width that is differentthan the other one of the first and second planar surfaces on that tip635 a, 635 b. As shown in FIG. 10D, the first planar surface 116 a ₁,116 b ₁ on each tip 635 a, 635 b has a width w₁ that is greater than awidth w₂ of the second planar surface 116 a ₂, 116 b ₂. As a result,each tip 635 a, 635 b will be offset from one another. In particular,the first planar surface 116 a ₁, 116 b ₁ of each 635 a, 635 b will bein facing relationship with one another, but the surfaces 116 a ₁, 116 b₁ will be offset. The first and second offset tips 635 a, 635 b can bepositioned in various ways, such as on opposed sides of a longitudinalaxis of the suture anchor 100 when the suture anchor 100 is notcompressed and is in a resting position. The offset tips 635 a, 635 bcan be spaced a distance apart from one another to allow a suture 90 tobe received in the slot or gap 122 defined therebetween. When the arms116 a, 116 b are compressed together upon insertion into a bone hole,the first planar surface 116 a ₁, 116 b ₁ of each tip 635 a, 635 b willcome into sliding contact with one another to thereby close the gap 122and form an enclosed eyelet 123, as shown in FIG. 10E. A suture disposedwithin the eyelet 123, however, will still be freely slidable.

The eyelet 123 can result from the arms 116 a, 116 b increasing in widthor thickness at the tips 635 a, 635 b. In particular, the first andsecond offset tips 635 a, 635 b can each have a maximum thickness t_(m)that is greater than a maximum thickness T_(m) of a proximal portion ofthe arms 116 a, 116 b. In other words, the tips 635 a, 635 b can be inthe form of protrusions formed on the inner surface of each arm 116 a,116 b.

The suture anchor can have various sizes, and by way of non-limitingexample the anchor can have a diameter of about 3.5 mm and a length ofabout 13 mm. The drill used to create the bone hole can vary based onvarious factors, such as the bone and the particular suture anchor beingused, but in one embodiment the drill can have a diameter of about 2.9mm and a length of approximately 9 mm long.

The suture anchor can be formed from various biocompatible materialsincluding, by way of non-limiting example, metals, such as surgicalgrade titanium, and polymers, such as poly-ether-ether-ketone (PEEK),polylactic acid, polyglycolic acid, and combinations thereof. Exemplarymaterials include, by way of non-limiting example, a composite oftricalcium phosphate and poly(lactic-co-glycolic acid), such as BiocrylRapide™ available from DePuy Mitek, Inc. Various portions of the sutureanchor 610 can also be formed from different materials to providedistinct advantages. For example, portions of the suture anchor 610 thatengage with the bone hole, such as the bone-engaging elements 332, maybe made of a material that is resilient to frictional forces, whereasthe portions of the flexible distal tip 635 that are compressible orflexible may be constructed from more compressible or flexiblematerials.

In use, a suture 90 can be passed through the open distal tips 635 a,635 b, and the anchor 100 can be inserted into a bone hole. The bonehole will cause compression of the distal tips 635 a, 635 b toward oneanother, thereby moving the first planar surfaces 116 a ₁, 116 b ₁ intosliding contact with one another. As a result, the tips 635 a, 635 bwill close forming an enclosed eyelet 123, which traps the suture 90therein. The tension of the suture 90 can be adjusted by sliding thesuture along the anchor. A knot or other fixation techniques can be usedto fix the suture and thereby anchor soft tissue coupled to the sutureto bone.

A person skilled in the art will appreciate that the suture anchorsdisclosed herein can be configured for use with one or more sutures. Theparticular quantity of sutures used with a suture anchor can depend onthe size of the suture anchor and the driver, and in particular on thediameter of the inner lumen of the suture anchor.

One skilled in the art will appreciate further features and advantagesof the invention based on the above-described embodiments. Accordingly,the invention is not to be limited by what has been particularly shownand described, except as indicated by the appended claims. Allpublications and references cited herein are expressly incorporatedherein by reference in their entirety.

What is claimed is:
 1. A suture anchor, comprising: an elongatesubstantially cylindrical body having a proximal portion with at leastone bone-engaging surface feature formed on an external surface thereof,a flexible distal portion, and an inner lumen extending between aproximal end and a distal end of the elongate body; and asuture-engaging member monolithic with and positioned within the innerlumen of the elongate substantially cylindrical body configured toreceive a suture there around, the elongate body being configured suchthat, upon insertion of the distal portion into a bone hole andengagement of at least one of the at least one bone-engaging surfacefeatures with the bone hole, a suture extending through the inner lumenand coupled to the suture engaging member is freely slidable, and theelongate body being further configured such that, upon further insertioninto the bone hole, the distal portion of the elongate body compressesradially inward against the suture-engaging member to lock the suturewithin the inner lumen such that the suture is prevented from sliding.2. The suture anchor of claim 1, wherein, when the distal portion of theelongate body compresses radially inward, an inner diameter of theproximal portion of the elongate body remains constant and an innerdiameter of the distal portion of the elongate body decreases to lockthe suture within the inner lumen.
 3. The suture anchor of claim 1,wherein the at least one bone-engaging surface feature comprises aplurality of circumferential ribs formed on the proximal portion of theelongate body.
 4. The suture anchor of claim 1, wherein the distalportion of the elongate body includes first and second opposed armshaving planar inner surfaces that move toward one another when the firstand second opposed arms are compressed radially inward.
 5. The sutureanchor of claim 1, wherein an outer diameter of the distal portion ofthe elongate body decreases in a distal direction.
 6. The suture anchorof claim 1, wherein the elongate body has a bore extending through asidewall thereof and in communication with the inner lumen.
 7. Thesuture anchor of claim 1, wherein the suture-engaging member includes atleast a portion that extends substantially transverse to an axis of theinner lumen.
 8. The suture anchor of claim 7, wherein thesuture-engaging member has a bore formed therethrough such that a suturecan pass through the suture-engaging member.
 9. The suture anchor ofclaim 7, wherein the suture-engaging member is U-shaped.
 10. The sutureanchor of claim 7, wherein the suture-engaging member extendssubstantially parallel to opposed planar inner surfaces of the distalportion of the elongate body.
 11. A suture anchor comprising: anelongate substantially cylindrical body having a proximal portion withat least one bone-engaging surface feature formed on an external surfacethereof, a flexible distal portion, and an inner lumen extending throughthe proximal and distal portions, wherein the elongate substantiallycylindrical body includes a bore extending through a sidewall thereofand in communication with the inner lumen, and wherein the flexibledistal portion includes a plurality of arms configured to be compressedradially inward when advanced into a bone hole so that an inner surfaceof at least one of the plurality of arms touches another one of theplurality of arms and compresses a suture therebetween to lock thesuture within the inner lumen such that the suture is prevented fromsliding.
 12. The suture anchor of claim 11, wherein the plurality ofarms of the distal portion of the elongate body taper radially inwardsuch that an outer diameter of the distal portion decreases in a distaldirection.
 13. The suture anchor of claim 11, wherein the bore is in thedistal portion of the elongate substantially cylindrical body.
 14. Thesuture anchor of claim 11, wherein the bore originates on an innersurface of the elongate substantially cylindrical body at a locationwithin the flexible distal portion and exits an outer sidewall of theelongate substantially cylindrical body at a location within theproximal portion.